Low cost binary phase shift keying modulation transmitter system

• US 5,859,869 A
• Filed: 11/17/1995
• Issued: 01/12/1999
• Est. Priority Date: 11/17/1995
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated, M&FC Holding, LLC
• Original Assignee: Sanconix Inc.
• Inventors: Sanderford, H. Britton
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US08/559,914
• Time in Patent Office: 1,152 Days
• Field of Search: 375/200, 375/206, 375/308, 332/103, 332/104, 332/105, 332/146, 380/46
• US Class Current: 375/130
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 2001/0491 with frequency synthesizers, frequency converters or modulators
• CPC Class Codes: H04L 27/2035 using a single or unspecified number of carriers

Abstract

An improvement in spread spectrum modulator systems, and more particularly further improvements in spread spectrum BPSK, or Binary Phase Shift Keying, Modulation systems, the present invention contemplating the utilization of an exclusive OR logic gate to replace an RF mixer stage in the SS transmitter, thereby providing enhanced gain at a lower energy consumption, with lesser cost and suppressed carrier output when compared to prior systems, as well as compatibility with CMOS low power logic modulation drive circuitry. The present system teaches a new, superior, and less costly BPSK transmitter than contemplated by the prior art, providing a less complicated system while outputting increased gain over prior art modulators.

Claims

1. A BPSK RF mixer, comprising:

a first exclusive OR gate A having an output, said gate A biased into a linear mode of operation, providing a linear output signal via said output, and configured to provide an even harmonic suppression;

a second exclusive OR gate B, said gate B having first and second inputs and an output, said first input coupled to said output of gate A, said second input of gate B configured to receive chip code modulation;

said first and second exclusive OR gates configured to form a dual gate cascade, wherein said linear output signal of gate A is coupled to said first input of gate B in such a manner as to bias said gate B into a linear mode of operation, and said chip code modulation inputed to said second input of gate B to provide modulation input, allowing said output of said gate B to directly produce BPSK modulation.

2. The BPSK RF mixer of claim 1, wherein said gate A further comprises first and second inputs, said second input brought to a logic high, configuring said gate A as an inverter.

3. The BPSK RF mixer of claim 2, wherein said output of gate A is directed to through a resistor and injected to said first input of said gate A.

4. The BPSK RF mixer of claim 2, wherein said first input of said gate A is injected with a filtered frequency signal via frequency multiplier.

5. The BPSK RF mixer of claim 1, wherein said gates A and B are CMOS.

6. The BPSK RF mixer of claim 1, wherein said output of gate B is filtered by a strip line filter, and is then amplified prior to transmission via antenna or the like.

7. The BPSK RF mixer of claim 5, wherein said gate B is provided by a following group of devices:

74AC, 74LVC, 74LVT, or BICMOS.

8. An RF mixer comprising:

a first exclusive OR gate A having an output, said gate A biased into a linear mode of operation, providing a linear output signal via said output, and configured to provide an even harmonic suppression;

a second exclusive OR gate B, said gate B having first and second inputs and an output, said first input coupled to said output of gate A, said first input further receiving a higher power input frequency, said second input of gate B configured to receive chip code modulation;

said first and second exclusive OR gates configured to urge said gate B into a linear region of operation, wherein said linear output signal of gate A is coupled to said first input of gate B, and said chip code modulation inputed to said second input of gate B to provide modulation input, allowing said output of said gate B to directly produce useable BPSK odd harmonics.

9. The RF mixer of claim 8, wherein said gate A further comprises first and second inputs, said second input brought to a logic high, configuring said gate A as an inverter.

10. The RF mixer of claim 9, wherein said output of gate A is directed to through a resistor and injected to said first input of said gate A.

11. The RF mixer of claim 8, wherein said first input of said gate A is injected with a filtered frequency signal via frequency multiplier.

12. The RF mixer of claim 8, wherein said gates A and B are CMOS.

13. The RF mixer of claim 8, wherein said output of gate B is filtered by a strip line filter, and is then amplified prior to transmission via antenna or the like.

14. The RF mixer of claim 12, wherein said gate B is provided by a device selected from the following group of devices:

74AC, 74LVC, 74LVT, or BICMOS.

15. The RF mixer of claim 12, wherein said gate B is provided by a SOP package comprising a 74LVC86 CMOS device.

16. A method of utilizing digital logic to replace an RF mixer stage in a spread spectrum transmitter, comprising the steps of:

a. providing a logic gate, comprising;

a first exclusive OR gate A having an output; and

a second exclusive OR gate B, said gate B having first and second inputs and an output,

b. configuring said gate A to provide an even harmonic suppression;

c. biasing said gate A into a linear mode of operation, such that said output of gate A provides a linear output signal;

d. configuring said first input of gate B to receive said output of gate A, and configuring said second input of gate B to receive chip code modulation;

e. forming a dual gate cascade, biasing said gate B into a linear mode of operation utilizing said linear output signal of gate A; and

f. utilizing said chip code modulation inputed into said second input of gate B to provide modulation input for producing BPSK modulation.

17. A method of utilizing digital logic to replace an RF mixer stage in a spread spectrum transmitter, comprising the steps of:

a. providing a logic gate, comprising;

a first exclusive OR gate A having an output; and

a second exclusive OR gate B, said gate B having first and second inputs and an output,

b. configuring said gate A to provide an even harmonic suppression;

c. biasing said gate A into a linear mode of operation, such that said output of gate A provides a linear output signal;

d. receive said output of gate A via said first input of gate B, while further receiving via said first input of gate B a higher power input frequency;

e. receiving chip code modulation via said second input of gate B;

e. forming a dual gate cascade, biasing said gate B into a linear mode of operation utilizing said linear output signal of gate A; and

f. utilizing said chip code modulation inputed into said second input of gate B to provide modulation input for producing useable BPSK odd harmonics.

18. A method of utilizing digital logic to replace an RF mixer stage in a spread spectrum transmitter, comprising the steps of:

a. providing a logic gate, comprising;

a first exclusive OR gate A having an input and an output; and

a second exclusive OR gate B, said gate B having first and second inputs and an output,

b. injecting said first input of gate A with a filtered frequency signal via frequency multiplier;

c. configuring said gate A to provide an even harmonic suppression;

d.. biasing said gate A into a linear mode of operation, such that said output of gate A provides a linear output signal;

e. configuring said first input of gate B to receive said output of gate A, and configuring said second input of gate B to receive chip code modulation;

f. forming a dual gate cascade, biasing said gate B into a linear mode of operation utilizing said linear output signal of gate A; and

g. utilizing said chip code modulation inputed into said second input of gate B to provide modulation input for producing BPSK modulation, via said output of gate B.

19. A method of utilizing digital logic to replace an RF mixer stage in a spread spectrum transmitter, comprising the steps of:

a. providing a logic gate, comprising;

a first exclusive OR gate A having an output; and

a second exclusive OR gate B, said gate B having first and second inputs and an output,

b. injecting said first input of gate A with a filtered frequency signal via frequency multiplier;

c. configuring said gate A to provide an even harmonic suppression;

d. biasing said gate A into a linear mode of operation, such that said output of gate A provides a linear output signal;

e. receive said output of gate A via said first input of gate B, while further receiving via said first input of gate B a higher power input frequency;

f. receiving chip code modulation via said second input of gate B;

g. forming a dual cascade, biasing said gate B into a linear mode of operation utilizing said linear output signal of gate A; and

h. utilizing said chip code modulation inputed into said second input of gate B to provide modulation input for producing useable BPSK odd harmonics.